With methods developed in our laboratory, we have been able to clone and maintain in culture three distinct cell types from either dissociated rat glomeruli or explants of whole glomeruli. The three cell types are: (1) glomerular epithelial cells (GEC); (2) a cell containing filaments which may be a mesangial cell; and (3) a renin-producing cell. GEC, and not the other two cell types, are susceptible to injury when cultured in the presence of either aminonucleoside of puromycin (AMNS) or nephrotoxic serum (NTS), agents which cause nephrosis in laboratory animals. We propose to examine the mechanisms of injury to GEC in vitro by analyzing; (1) glycocalyx synthesis and turnover; (2) calcium fluxes; (3) cell surface events such as changes in charge and adhesive properties; (4) changes in microtubules and microfilaments which affect cell shapes; and (5) the effect of metabolites of ANMS. Since our mesangial cell is not phagocytic, we will do the following experiments to help us analyze its role in glomerular function; (1) contractility experiments; and (2) response of these cells (and the other cells) to various hormones (e.g., ADH, PTH, PGE2) in relation to cyclic nucleotide levels. Mechanisms of renin metabolism and release will be analyzed with our homogeneous population of renin-producing cells (e.g., beta-adrenergic stimulation, PGE2, cAMP, etc.). Renin synthesis and release will be studied in mice maintained on a low salt diet (which stimulates renin synthesis and release). In particular, the structural and cellular events will be evaluated by ultrastructural autoradiography and cytochemistry, and by immunocytochemistry.